Here is a cool 3D scatterplot using mtcars.

It shows the relationship between horsepower, weight, and miles per gallon in the mtcars dataset. Cylinder count is represented by color and displacement by size.

# 3D Scatter plot with mtcars
plot_ly(
  data = mtcars,
  x = ~hp,   # Horsepower
  y = ~wt,   # Weight
  z = ~mpg,  # Miles per gallon
  color = ~factor(cyl), # Cylinder count
  size = ~disp,         # Displacement for marker size
  colors = c('red','green','blue'),
  type = 'scatter3d',
  mode = 'markers',
  marker = list(symbol = 'circle', sizemode = 'diameter', opacity = 0.8)
) %>%
  layout(
    scene = list(
      xaxis = list(title = "Horsepower (hp)"),
      yaxis = list(title = "Weight (1000 lbs)"),
      zaxis = list(title = "Miles per Gallon (mpg)")
    ),
    title = "3D Scatter Plot of mtcars"
  )
## Warning: `line.width` does not currently support multiple values.
## Warning: `line.width` does not currently support multiple values.
## Warning: `line.width` does not currently support multiple values.